1. Field of the Invention
The present invention relates to the field of Radio Frequency (RF) tagging, and more particularly, to a particular remote RF transponder (tag) that is specifically identified by an incoming RF identification (RFID) signal, wherein the specifically identified tag wakes up a data storage device from a zero power state to an operational state so that data transfer between the data storage device and a data administrator may take place independently of the RFID signal.
2. Description of Related Art
RF tags have been used in many applications. For example, in a vehicle immobilization application, a vehicle motor will only start when a changeable code is passed from a tag in an ignition key to a circuit that is connected to the vehicle engine. The tag is not electrically connected to the circuit. Also, a complex tag reader is needed for each engine circuit that is to be enabled/disabled. The relatively simple tag in the key has to be in a specific location with respect to the tag reader to allow the reader to access the code on the tag. Further, the tag reader requires power from some source associated with the enabled/disabled circuit. Because of the complexity, expense, and power requirements of the tag reader, this system is limited to expensive, enable/disable circuits with relatively unlimited amounts of on-board power. Further, since the tag and the reader must be adjacent to each other for the reading to occur, no remote communication with the tag is involved in the enabling/disabling operation.
RF tagging systems are also used to prevent theft in the retail industry, e.g., retail sales of electronic equipment. One prior approach to this problem is to place a tag on the item. These systems rely on a reader being able to detect the tag as it leaves a designated retail trade area, and activate an alarm when a stolen item is detected.
In another use of RF tagging systems to prevent theft of retail items in the retail industry, a base station transmits RF signals received by an RF tag. Memory of the RF tag is provided with data that controls an enabler/disabler interface circuit of the tag. An interface circuit controls an external electronic circuit within the retail item. A critical part of the external electronic circuit has states controlled by the interface circuit for enabling and/or disabling operation of the electronic circuit. If the sale of the retail item has not been authorized, for example, the operation of the electronic circuit is not permitted. In this retail anti-theft application, no problem is presented as to maximizing the life of a limited power-capacity power source (such as a battery) contained in an electronic circuit having an infrequently used duty cycle. Further, this type of retail anti-theft application does not present a problem of how to remotely change the data stored in the retail item, nor how to communicate with the retail item after the item has passed through a control point at which a change of the enabling/disabling state occurs if the sale has been authorized. Also, the tag initiates the enabling or disabling functions, but not the actual operation of the electronic circuit for its intended purpose.
RF tags have been used in other applications. For example, attempts have been made to communicate with electronic units that are remote from a base station. The remoteness may be in terms of tens or hundreds of miles separating the base station and the unit, or in terms of the unit being mobile, such as being on a truck that may be difficult to access or service due to distant, unpredictable routes of travel. One prior attempt to solve the communication problem required the electronic unit to remain in a standby state in which power is drawn from a limited power-capacity power source (such as a battery) of the electronic unit merely to maintain continued responsiveness to infrequent RF signals from the remote base station. A typical unit having standby operation may include a clock that causes a dual mode power supply to continuously provide power needed for the standby operation, except when operation for communications is required. Because of the infrequency of the RF signals which request communications, the amount of power used for maintaining the continuous standby state dominates the total power used for the communications. Further, where the communications are intended to transfer large amounts of data, the data storage capacity of the RF tag is inadequate, e.g., is limited to an approximate data storage range between 64 bits and 1024 bits, and more typically about 256 bits.
Other attempts have been made to communicate with electronic units that are remote from a base station. For example, when base station on/off signals are provided by a clock, an interrogation operation may periodically provide the RF tag with power to determine whether the base station is polling the RF tag. As in the standby situation, because of the infrequency of the RF signals which request communications, the amount of power used for providing the periodic power to the RF tag dominates the total power used for the communications. In both such standby and polling situations, high amounts of power are used for operating the clock and for the periodic powering of the tag or the standby power, which are the dominant power usages.
Other attempts have been made to communicate with a unit that is remote from a base station. The unit may be on a truck or railroad car, for example, and is provided with operating power from a battery or power generating sources. An exemplary remote unit of this type is shown in U.S. Pat. No. 4,870,419. In one embodiment a microwave signal is transmitted and received by the remote unit having a logic circuit and memory, a trigger circuit, and a transmitter. The transmitter cycles from a low-power usage quiescent state to a battery-operated operational state. The transmitter is used to transmit the relatively small amount of data that is stored in a memory bank of the unit (e.g., 256 bits). Code rates for microwave antennas of the remote unit are apparently selected so that communications between the remote unit and a central interrogation station may occur as the railroad car passes one or more of the interrogation stations. The trigger circuit is a passive circuit deriving operational power from a triggering signal in the form of a burst of microwave energy or an RF signal from the interrogation station. However, as understood the triggering signal does not attempt to identify a specific one of the remote units that is to be operated. As a result, it appears that any such remote unit that is within the burst of microwave energy, for example, would be triggered and become operational. Also, in the remote unit shown in U.S. Pat. No. 4,870,419, there is a limit to the amount of data to be communicated between the remote unit and the interrogator. The limit is based on railroad or highway speeds and the window of a microwave antenna, for example, indicating that communication occurs only via the microwave or other trigger signal received by the trigger circuit antenna of the unit or sent by the transmitter antenna of the unit. Thus, it appears that only very limited amounts of information can be communicated during a brief period of transmission, which corresponds to the limited amount of information that can be stored in the very low data storage-capacity memory bank of the unit. As a result, there is no provision for continuing the communications between a unit and the interrogation station after the unit passes the central station.
In view of the forgoing, what is needed is a remote RFID tag that is specifically identified by an incoming RFID signal, wherein the specifically identified tag wakes up a high data capacity data storage device from a zero power state to an operational state so that data transfer between the data storage device and a data administrator may take place independently of the RFID signal.
Broadly speaking, the present invention fills these needs by providing a remote system including a radio frequency identification (RFID) tag that is specifically and periodically identified by an RFID signal. The specific RFID tag is associated with a particular remote data transfer device. When identified, the specific RFID tag changes the state of the associated remote data transfer device from a zero power state to an operational state. In this manner, the limited power-capacity of a remote power supply is used solely for data transfer between the data transfer device and an administrator and not at all for standby or periodic powering of non-data transfer operations.
In the present invention, although many RFID signals may be transmitted over time to the location of many remote systems, each of which has an RFID tag, an RFID signal is only infrequently sent to a specific one of the RFID tags. That is, such an RFID signal is transmitted only to request a data transfer operation with the particular remote data transfer device that is associated with that specific RFID tag. Further, at the end of the operational (i.e., data transfer) state of that particular remote data transfer device, the state of that data storage device is returned to the zero power state. Each RFID tag is preferrably a passive beam-powered tag. As a result of factors such as: (1) the zero power state, (2) the specificity and periodicity of the RFID signal, (3) such return to the zero power state, and (4) the use of the specific selected passive beam-powered RFID tag, the zero power state is the primary state from a temporal standpoint, such that for substantial periods of time no power is drawn from the limited power-capacity of the remote power supply.
Another aspect of the present invention is that the data storage device may be provided in many different electronic units, all of which may involve data transfer. Such units may include, for example, one or more computers, databases, cellular telephones, sensors that generate data, etc. In this manner, the data storage capacity of the remote system is not limited to the inherently very limited data storage capacity of the passive beam-powered RFID tag.
Yet another aspect of the present invention is to provide the remote system with a wireless local area network (WLAN) accessible to a particular remote data storage device for communicating with an administrator that may request a data transfer operation with that particular remote data storage device. The data transfer is effected over the WLAN and may be data transferred to or from, or both to and from, the particular remote data storage device. In any case, the data transfer may be between the administrator and the particular remote data storage device, or between the particular remote data storage device and another remote unit serviced by the administrator, e.g., a system that monitors or provides the data that is transferred.
A further aspect of the present invention relates to the particular remote system being mobile. For example, the passive beam-powered RFID tag and the particular remote data storage device may be mounted on a truck for monitoring the kind and amount of cargo carried by the truck at any given time. Or, such tag and data storage device may be part of a mobile cellular telephone. In these cases, the WLAN enables a data transfer operation to take place with the particular remote data storage device independently of the incoming RFID signal. As a result, once the specific RFID tag has been selected, the incoming RFID signal is no longer needed, and data transfer with the particular remote data storage device takes place via the WLAN or other suitable wireless communication connection.
In still another aspect of the present invention, a selected remote data transfer device, including a particular remote data storage device and WLAN, are provided with operating power only when the specific RFID tag associated with such particular remote data storage device and WLAN has been selected.
Additionally, an aspect of the present invention includes a method of periodically providing data to or from a remote area. The method may include operations of providing a plurality of individual data storage units in the remote area. Each of the remote data storage units is normally in a zero power (OFF) state, has an operational (ON) state for operation, and has a data storage capacity that is large relative to that of a typical RFID frequency tag. A unique RFID signal is periodically transmitted to the remote area only at a separate specific time at which it is desired to provide data to or from a particular one of the data storage units that corresponds to the unique signal. Thus, each unique individual one of the RFID signals is designed to identify only the particular one of the remote data storage units that is selected. In response to the unique RFID signal, the particular one of the data storage units is thus selected, e.g., identified, and then caused to be in the operational state. In the operational state, data is transferred to and from that selected data storage unit via a wireless local area network (WLAN). Thus, data communication is established with a particular remote data storage unit only when that data storage unit is selected and is in the operational state, and independent of the RFID signal.
Another aspect of the present invention involves a plurality of service provider units for use at remote locations. The provided services may relate to data transfer, with each service provider having data unique to it. Each unit has a power supply with a low total power-capacity. A particular unit responds to a request unique to it from a requesting station located away from the remote location of the unit. The requesting station transmits to the remote location periodic unique service-request signals. The signals include a signal requesting data-type data transfer service from a specific one of the service provider units. The data-type data transfer service is different from more frequent polling-type data transfer that may occur in prior art systems for frequently determining whether the requesting station is currently attempting to locate the particular unit. The service provider unit may include a radio frequency identification (RFID) tag responsive to only one of the unique service-request signals for generating a wake-up signal. A particular remote service provider is associated with a specific one of the RFID tags. That particular provider has a zero power (OFF) state when no power is provided to it and has an operational (ON) state when power is supplied to it. In the operational state the particular service provider transfers its particular data with the requesting station. A power source is connected to the particular service provider to supply the low total amount of power of the low total power-capacity. The power source is used only for the infrequently used data-type data transfer service. That is, because there is no use of such power source for frequent polling-type data transfer, substantially all of the low total power-capacity of the power source is available for the infrequently requested-data-type data transfers. As a result, almost all of the useful life of a battery having the low total power-capacity is used for providing the infrequently requested-data-type data transfers.
Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.